The invention concerns an alternative to the Maltese cross system, whose function is to convert a continuous rotation into a jerky rotation. This may consist, for example, in rotating a wheel by one step (often a quarter turn) when it passes an irregularity (complementary shape) on a drive wheel set which is subjected to a continuous rotation. This system is, for example, used in horology to make a stopwork, or in perpetual calendar mechanisms to rotate a leap year cam by one quarter turn at each year change.
Such a system is very practical since it uses virtually no energy upon the rotation. Indeed, it does not require a jumper spring to hold the wheel, since its rotation is directly locked by the drive wheel in the event of a shock. This applies to wheels that are not subjected to a torque, but does not apply in the case where the wheel is subjected to a permanent or non-permanent torque. Indeed, the friction generated at the interface between the wheel and the drive wheel represents a permanent consumption of energy proportional to the forces present on the latter.